Followup: Cletus is a variant of a Greco-Latin name. How/when did it become stereotyped as a "hillbilly name"? (E.g. Cletus Spuckler on Simpsons).
/u/Cosmic_Charlie has an old answer about names of enslaved people that covers classical/Roman names!
(Just keep in mind the answer is from four years ago, when the average answer wasn't as long or detailed.)